An internal combustion engine may be used to provide motive power to vehicles. It will be appreciated that the term internal combustion engine includes diesel engines, spark ignition engines, hybrid internal combustion engines, etc.
During cold engine starts, engine oil may be below a desired temperature. As a result, combustion efficiency may be decreased and emissions may be increased. Attempts have been made to actively warm oil via a heating apparatus. The heating apparatus may increase the cost of the engine. Furthermore, the heating apparatus may not heat the oil in a desired duration.
Other attempts have been made to store the engine oil which is warmed during operation in an insulated container, so that, when the internal combustion engine is started again, pre-warmed oil is available. A drawback with this procedure is that the oil which has been warmed during operation cannot be kept for unlimited time at a desired temperature, so that a renewed warming of the oil in the warm-up phase of the internal combustion engine may be desired. Additionally, heat may be removed from the oil as it flows through the crankcase, which after a cold start is not warmed by combustion operation in the engine. The heating apparatus and/or insulated container may not provide a desired amount of heat to the oil to counteract the cooling of the oil in the crankcase after a cold start. For example, warmed oil may be cooled as it travels through the crankcase, due to the cold engine structure, on its way to oil consuming devices (e.g., crankshaft bearings).
Further, the cylinder block and/or the cylinder head of an internal combustion engine are a thermally stressed component and therefore may be equipped with a fluid cooling system. The heat balance of the internal combustion engine may be controlled by this cooling, which may make rapid warming of the engine oil during the warm-up phase difficult to achieve.
To solve at least some of the aforementioned problems, a lubrication system in an internal combustion engine is provided. The lubrication system includes a crankshaft bearing supporting a crankshaft, a supply line including an outlet flowing oil to the crankshaft bearing and an inlet receiving oil from an oil gallery, and thermal insulation at least partially surrounding at least a portion of an inner wall of the supply line and/or the oil gallery.
In this way, the oil-carrying lines may be provided with insulation which decreases heat transfer from the oil to the cylinder block and/or surrounding environment. As a result, the oil provided to the bearing may be at a desirable temperature.
The thermal insulation may include a polymeric material in some examples. The polymeric material may provide desired insulation properties. Specifically, polymeric material has a low heat transfer coefficient and possesses low conductivity and therefore may act as a heat barrier, thereby reducing the heat flow from the oil to the cylinder block, as compared to metal components.
Further in some examples, the thermal insulation may include a treatment applied to the surface of the inner wall. For example, an anodic oxidation may be applied in an electrolytic process, in which an oxide layer is produced on the surface of the inner wall, which is distinguished by a substantially higher strength but also has properties for the formation of a heat barrier. Another advantage of the surface treatment is that—for example, in anodization—the oxide layer grows from the surface into the material or metal, so that the geometric dimensions of the oil-carrying lines may remain unaltered, if desired.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.
The internal combustion engine is described in greater detail below with reference to the illustrative examples shown in FIGS. 1-3.